1. Field of the Invention
The present invention relates to a high frequency wave glass antenna for an automobile, which is suitable for receiving signals in the FM broadcast band (76 to 90 MHz) in Japan or in the FM broadcast band (88 to 108 MHz) in USA. Hereinbelow, the FM broadband in Japan and the FM broadband in USA will be simply referred to as the FM broadcast band.
2. Discussion of Background
A high frequency wave glass antenna for an automobile, which is provided on the glass sheet 1 for a rear side window of an automobile to receive broadcast signals as shown in FIG. 2, has been employed. In FIG. 2, the glass sheet 1 has an antenna conductor 23 and a power feeding point 23a provided thereon. The antenna conductor 23 is made of a conductive pattern, which is prepared by, e.g., a method to print paste containing electrically conductive metallic materials, such as electrically conductive silver paste, on an interior side of the glass sheet 1 and to bake the printed paste. The antenna conductor is utilized as an antenna.
In the conventional glass antenna, signals received by the antenna conductor 23 are transmitted from the power feeding point 23a to a preamplifier for FM (not shown) through a coaxial cable (not shown). The preamplifier amplifies the received signals and transmits the amplified signals to a receiver (not shown). The antenna conductor 23 serves as not only an antenna for the FM broadcast band but also an antenna for an AM broadcast band.
When receiving signals, the high frequency wave glass antenna for an automobile shown in FIG. 2 serves as a monopole antenna for transmitting the received signals at the power feeding point to the receiver. In the high frequency wave glass antenna for an automobile shown in FIG. 2, the coaxial cable has an internal conductor connected to the power feeding point and an outer conductor connected to a metallic automobile body.
The high frequency wave glass antenna for an automobile shown in FIG. 2 has caused a problem that the conductor length is not enough to have good sensitivity to signals in the FM broadcast band. The conventional glass antenna has also caused a problem that visibility is not good since the pattern forming the antenna conductor is provided in the vicinity of the substantially center on the glass sheet 1 for a rear side window.
It is an object of the present invention to provide a high frequency wave glass antenna for an automobile, which is capable of solving the problems of the conventional antenna stated earlier.
The present invention provides a high frequency wave glass antenna for an automobile, comprising a primary antenna conductor, a grounding conductor, a power feeding point for the primary antenna conductor and a grounded point for the grounding conductor provided on or in a glass sheet of a window of an automobile; wherein the power feeding point and the grounded point are provided so as to be located in the vicinity of a peripheral portion of the glass sheet or an opening edge formed in an automobile body; wherein when seen from an interior side or an exterior side of the automobile, the primary antenna conductor extends in a counterclockwise direction, beginning at the power feeding point; wherein two portions of the primary antenna conductor are connected by a loop-forming conductor to form a loop conductor by the primary antenna conductor and the loop-forming conductor, or a portion of the primary antenna conductor and the power feeding point are connected by a loop-forming conductor to form a loop conductor by the primary antenna conductor, the loop-forming conductor and the power feeding point; and wherein a portion or an entire portion of the grounding conductor is located near to and capacitively coupled with at least one of the primary antenna conductor, the loop-forming conductor and the power feeding point.
The present invention also provides a high frequency wave glass antenna for an automobile, comprising a primary antenna conductor, a grounding conductor, a power feeding point for the primary antenna conductor and a grounded point for the grounding conductor provided on or in a glass sheet of a window of an automobile; wherein the power feeding point and the grounded point are provided so as to be located in the vicinity of a peripheral portion of the glass sheet or an opening edge formed in an automobile body; wherein when seen from an interior side or an exterior side of the automobile, the primary antenna conductor extends in a counterclockwise direction, beginning at the power feeding point; wherein two portions of the primary antenna conductor are connected by a first loop-forming conductor to form a loop conductor by the primary antenna conductor and the first loop-forming conductor, or a portion of the primary antenna conductor and the power feeding point are connected by a first loop-forming conductor to form a first loop conductor by the primary antenna conductor, the first loop-forming conductor and the power feeding point; wherein two portions of the primary antenna conductor, which are not contained in the first loop conductor, are connected by a second loop-forming conductor to form a second loop conductor by the primary antenna conductor and the second loop-forming conductor; and wherein a portion or an entire portion of the grounding conductor is located near to and capacitively coupled with at least one of the primary antenna conductor, the first loop-forming conductor, the second loop-forming conductor and the power feeding point.
The present invention also provides a high frequency wave glass antenna for an automobile, comprising a primary antenna conductor, a grounding conductor, a power feeding point for the primary antenna conductor and a grounded point for the grounding conductor provided on or in a glass sheet of a window of an automobile; wherein the power feeding point and the grounded point are provided so as to be located in the vicinity of a peripheral portion of the glass sheet or an opening edge formed in an automobile body; wherein when seen from an interior side or an exterior side of the automobile, the primary antenna conductor is provided so as to extend, in a counterclockwise direction, to at least a lower side of the glass sheet substantially along the peripheral portion of the glass sheet or the opening edge, beginning at the power feeding point; wherein two portions of the primary antenna conductor are connected by a loop-forming conductor to form a loop conductor by the primary antenna conductor and the loop-forming conductor, or a portion of the primary antenna conductor and the power feeding point are connected by a loop-forming conductor to form a loop conductor by the primary antenna conductor, the loop-forming conductor and the power feeding point; and wherein a portion or an entire portion of the grounding conductor, which extends beginning at the grounded point, is located near to and capacitively coupled with at least one of a lower portion of the primary antenna conductor and the loop-forming conductor.